Aer Lingus has been in discussion with three potential partners interested in buying a substantial stake in its TEAM Aer Lingus subsidiary. It believes it could quickly tie up a deal with one of them, if it can get trade union agreement on a number of controversial industrial relations issues.

However SIPTU warned last night that existing agreements must be honoured and branch secretary Mr Paul O'Sullivan said that employees were "gravely disappointed" with the lack of information from the group on the proposed investors. Mr Gary McGann, the Aer Lingus chief executive, briefed the TEAM unions on the issue yesterday, warning that "unless outstanding issues in relation to costs and future committed business can be progressed, its future could be undermined."

The key issue on which the Aer Lingus management is seeking change is on the controversial letters of comfort held by some 1100 of the 1550 TEAM staff. The unions say that these letters guarantee their members the same terms and conditions as Aer Lingus employees, but the group management is arguing that they are no longer valid. The issue has become even more live after the SIPTU members of Aer Lingus voted in favour of a plan drawn up by former senior trade unionist, Mr Phil Flynn, which involves phased pay increases of 5.5 per cent in return for agreement to negotiate on cost savings of £50 million over five years. Mr Flynn's plan said that these terms should not apply to TEAM employees. In a strongly worded statement referring to the letters of comfort last night, SIPTU, which represents 600 of the TEAM workers, said that most of its members " are Aer Lingus employees and SIPTU insists that these contracts will have to be honoured in full." SIPTU also called on Aer Lingus management to disclose all information relating to the finances and future of TEAM, saying that yesterday's briefing came completely "out of the blue."

Last night an Aer Lingus spokesman said that the trade unions were being briefed at a time when no concrete agreement on the terms of a strategic alliance deal had been discussed.

According to a statement from Mr McGann, the discussions with potential partners " have been of a preparatory nature and no final shape has been put on any potential deal." Difficult discussions between trade unions and management now lie ahead, with Mr McGann warning that " the window of opportunity for TEAM to secure its position in this changing marketplace is very narrow."

While management has had discussions with three potential partners, it is understood that talks with one are particularly advanced. Management is believed to be confident of tying up a strategic alliance deal in a matter of weeks, if it can get agreement with the trade unions on the outstanding issues. The potential shape of a strategic alliance is not clear. When TEAM was split from Aer Lingus, there was a commitment that the parent would retain a majority stake. However any strategic alliance partner may look for a majority stake - or an option to move to a majority stake in future. Aer Lingus has already sold a 90 per cent share in engine overhaul business Aermotive to Lufthansa.

The move to forge a strategic alliance for TEAM comes as industry analysts believe that the aircraft maintenance sector is heading for a period of major consolidation, in common with what has already happened in other parts of the aircraft industry. In this environment, Aer Lingus management will be keen that TEAM becomes part of a larger international operation. TEAM's performance has been improving in recent years in line with industry trends. It lost £5.5 million in the year to last December on turnover of £84 million and is on target - or possibly ahead of target - to meet its five year plan of being in profit by 1999.